From: | Christopher Petrilli <petrilli(at)gmail(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | PFC <lists(at)boutiquenumerique(dot)com>, Vivek Khera <vivek(at)khera(dot)org>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Impact of checkpoint_segments under continual load conditions |
Date: | 2005-07-19 17:13:05 |
Message-ID: | 59d991c405071910133e28031a@mail.gmail.com |
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Lists: | pgsql-performance |
On 7/19/05, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Christopher Petrilli <petrilli(at)gmail(dot)com> writes:
> > As I'm doing this, I'm noticing something *VERY* disturbing to me:
> > postmaster backend: 20.3% CPU
> > psql frontend: 61.2% CPU
>
> > WTF? The only thing going through the front end is the COPY command,
> > and it's sent to the backend to read from a file?
>
> Are you sure the backend is reading directly from the file, and not
> through psql? (\copy, or COPY FROM STDIN, would go through psql.)
The exact command is:
COPY test (columnlist...) FROM '/tmp/loadfile';
> But even so that seems awfully high, considering how little work psql
> has to do compared to the backend. Has anyone ever profiled psql doing
> this sort of thing? I know I've spent all my time looking at the
> backend ...
Linux 2.6, ext3, data=writeback
It's flipped now (stil lrunning), and it's 48% postmaster, 36% psql,
but anything more than 1-2% seems absurd.
Chris
--
| Christopher Petrilli
| petrilli(at)gmail(dot)com
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